Fonus Behind-the-neck style 3.5mm Sport Headphones Handsfree Neckband Headset Earbuds Compatible with AT&T Sonim XP7 Cell Phones. Fonus Street Style Neckband Headphones give you the freedom to enjoy your music and workout without any interference. These headphones are great for athletes, personal trainers, fitness enthusiasts and those who are continuously involved in physical activity or on-the-go. Enjoy features such as a sweat resistant guard design and rich sound quality. Easy to carry in your gym bag, backpack, or in your pocket, the lightweight and compact design of the Fonus headphones allows you to conveniently take them anywhere on-the-go.